This invention relates to a fluid pump control system for regulating the speed of a pump in accordance with the fluid supply so that the pump does not impose a back pressure on the source of supply by running too slowly and does not create suction pressure on the source of supply by running too fast. The invention is of general application for the specified purpose but it is disclosed herein with particular reference to an extracorporeal blood circuit for a patient. This invention is an improvement on the control system in the Edwards U.S. Pat. No. 3,827,828.
Open heart practices are today very well established as applied to surgical procedures where the normal blood supply to the muscles of the heart and to the brain must not be interrupted during repair of critical organs.
With the advancement of the art of fabricating membrane oxygenators, which are notably low in damage to the blood, there has been a need for developing new procedures to permit long time perfusion of a patient during periods of crisis. Patients suffering from heart attack, emphysema, asthma, or the like, may over a period of days with supplementary perfusion with well oxygenated blood develop sufficient recovery of natural organ functions to carry on without the need of the extracorporeal blood supply.
To do this it is desirable to make connection through catheterized connections to more peripheral blood vessels of the body. This avoids the necessity of opening the patient's chest for access to the larger vessels near the heart.
It is also important to provide the equipment which will permit carrying on the longer period of a procedure in an intensive care area of the hospital without usurping a surgical area for the extended period.
The present system makes it possible to operate an extracorporeal blood circuit without the close attention of a skilled pump attendant as is usually employed in cases where a short term profusion is indicated as is usual during heart syrgery.
During heart surgery, a pump and oxygenator takes over the normal functions of the heart and lungs to circulate and oxygenate the blood in order to keep those organs of the patient alive which require a continuous supply of fresh blood. An array of mechanical equipment attended by a team of specialists is necessary to do this in addition to the team of surgeons who perform the operation. One of the functions which demands constant attention is to maintain a proper speed of the blood pump so as not to let the extracorporeal circuit become too out of phase with blood supply and demands of the perfused organs. The purpose of the present device is to regulate the pump automatically so that manual supervision is not required.
Objects of the invention are, therefore, to provide an improved fluid pump control system, to provide a pump control system which regulates the speed of the pump according to the rate of flow of its source of supply, to control a pump so that it does not impose a back pressure on its source of supply by running too slowly and does not create suction pressure in its source of supply by running too fast, to provide an electric control system for the purpose described which is operable on standard 120 volt alternating current house wiring, and to provide a control system of the type described which is suitable for use in connection with the flow of blood in an extracorporeal blood circuit.